"Bertelsmann confirms its intention to reduce its shareholding in RTL Group by way of a secondary public offering," the German group said in a statement.
"The transaction would result in a significant increase of the free float in RTL Group shares, with Bertelsmann maintaining a qualified majority of at least 75 percent."
Bertelsmann currently holds a stake of 92.3 percent in RTL, with 7.7 percent in free float.
The shares would be offered "to private and institutional investors in Germany and Luxembourg through a public offering," the statement said.
"Outside of these countries, it is intended to offer shares to institutional investors via private placements."
RTL, which is listed on the Luxembourg stock exchange and Euronext in Brussels, said it intends to list its shares in Frankfurt, too, with the first day of trading for the offered shares expected "before the summer break."
The fact that Bertelsmann intends to maintain a stake of at least 75 percent shows that "Bertelsmann remains convinced of the highly attractive and positive long-term outlook for RTL Group's free-to-air TV and radio broadcasting as well as TV production businesses," the broadcaster said.
"Bertelsmann is and will remain the majority shareholder in RTL Group and will continue to support the strategic development of our business. The reduction of Bertelsmann's shareholding would significantly increase the free float of RTL Group shares, enabling a more diverse ownership base to share in our success," said RTL's co-chief executives Anke Schaferkordt and Guillaume de Posch.
Because the shares were being offered by Bertelsmann, "RTL Group will not raise new capital in connection with the public offering and will not receive any of the proceeds from it," RTL added.